${alpha}$-Neoagarooligosaccharide (${alpha}$-NAOS) hydrolase was purified from Cellvibrio sp. OA-2007 by using chromatographic techniques after hydroxyapatite adsorption. The molecular masses of ${alpha}$-NAOS hydrolase estimated using SDS-PAGE and gel filtration chromatography were 40 and 93 kDa, respectively, and the optimal temperature and pH for the enzyme activity were $32^{circ}C$ and 7.0-7.2. ${alpha}$-NAOS hydrolase lost 43% of its original activity when incubated at $35^{circ}C$ for 30 min. The enzyme hydrolyzed neoagarobiose, neoagarotetraose, and neoagarohexaose to galactose, agarotriose, and agaropentaose, respectively, and produced 3,6-anhydro-L-galactose concomitantly; however, it did not degrade agarose.